Abiotic stresses are key limiting factors that restrict rice production. Among them, drought is one of the major factors that induce several physiological, biochemical and molecular responses in plants. Screening of rice varieties against drought stress is a prerequisite to produce stress tolerant rice varieties. Two rice varieties, i.e. Godaheenati (4049) and Pokkali were screened for drought stress responses based on biochemical attributes at the seedling stage. Relative water content, the total protein content of leaves of two-week-old rice seedlings and photosynthetic pigment levels were measured over a fiveday drought period. The varieties tested responded with different relative water content, protein concentrations and pigment levels, potentially due to their genetic differences. Godaheenati showed an increase of the relative water content on the fourth day under drought stress, indicative of its cell recovering capability, and thus may be drought tolerant than Pokkali. Dehydration stress resulted in the fluctuation of all three photosynthetic pigments in both varieties. On the fourth day, Godaheenatishowed a significant increase of photosynthetic pigments than Pokkali, and this could be a result of recovery of plant cells due to the increase of water content. The total protein content extracted from leaves of twoweek-old rice seedlings of Godaheenati exposed to drought conditions was subjected to twodimensional gel electrophoresis.The results showed alterations in the total proteome of rice leaves, and an up regulation of genes responsible for drought stress tolerance in rice. Further screening is recommended for Godaheenati as a drought tolerant rice variety to be used in rice breeding programs.

Morphological variation of 16 rice accessions representing both traditional and improved varieties was assessed using 12 vegetative traits as described in International Rice Research Institute descriptor for rice, in sand medium using a Complete Randomized Design. The single linkage clustering, morphological dendrogram, multivariate analysis of variance and the Principal Components Analysis were performed to assess the traits. According to the cluster analysis, accessions 2840 and 10617 were the most closely associated among the varieties. Based on the variations associated with morphologically important vegetative traits, all the rice accessions were classified into three major groups as two traditional and one new improved variety groups. Existence of such clusters was validated by the Wilks' lambda statistics. The first four principle components explained over 80% of the total variation associated with the varieties. Among them the first two principle component cumulatively explained 54.46% of the total variation. Rice accessions 8920 and 2835 representing Bg360 and Bg 450, respectively showed the highest principle component 1scores. Traditional rice varieties showed the comparatively higher scores in both principle components 1 and 2 than newly improved varieties. This study indicated that measured vegetative agro-morphological traits were helpful for preliminary characterization of varieties and also they can be used as a broad-spectrum approach to assess morphological diversity among morphologically distinguishable rice accessions.

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The genus Dendrobium is one of the largest genera in the family Orchidaceae having more than thousand species over the world with diverse morphological characters. Dendrobium is a popular ornamental plant with complex genetic background which emphasize on the species identification at molecular level. The present study was aimed to identify Inter-Simple Sequence Repeat (ISSR) markers capable of detecting genetic polymorphism to characterize 18 hybrid, commercially available Dendrobium cultivars. Genomic DNA of each cultivar was extracted using CTAB method. A total of 17 different ISSR primers were evaluated. Only the reproducible bands were scored and number of different alleles (Na), number of effective alleles (Ne), Shannon’s Information Index (I), Expected heterozygosity (He), Unbiased expected heterozygosity (UHe), polymorphic percentage and polymorphic information content (PIC) of each primer were calculated. The highest Shannon’s Information Index (0.537±0.08) was recorded by the primer UBC 826 while the highest polymorphic information content (PIC) was generated by primer UBC 807. The PIC values of the primers were ranged from 0.0068 to 0.451, indicating that primers are moderately informative. In total, 631 bands representing 120 loci were amplified showing 85.71% - 100% polymorphism. The genetic similarities between individuals were compiled in the Nei’s genetic identity matrix in order to construct the UPGMA dendrogram. Principle component analysis (PCA) and clustering analysis were done to divide different cultivars into groups. The analysis revealed the presence of four major clusters and two minor clusters among the cultivars. The study suggested that the ISSR markers originated from eight primers 12, 155, UBC 807, UBC 812, UBC 826, UBC 835, UBC 841 and UBC 842 can be used in the detection of molecular variation among cultivars in the genus Dendrobium.

Sustainability of transplanting systems for rice crop establishment in Sri